body and interior Hot Air from Heater Box

[2002#3]

I have "overhauled"/"refurbished" my heater box (HB) 3 times to the point of it's working increasingly better each time.  Now it seems to work as intended.  (Yes, it took 3 times.  I am setting new records for decreasing times required to remove and install a HB.)  Seals, bushings, flaps, heater valve (HV), Bowden cables and adjustments, flushed HB radiator, epoxyed cracks, lubrication, lever functions, misc. adjustments,  etc.  All seems to open, close, flow, blow, defrost, and function exceedingly well.  3-speed fan works swimmingly.  

 

However, with the temp lever on COLD (HV closed) and the flow lever on HEAT (allows air into the footwell; HB radiator flap closed), the air from the HB into the footwell usually is uncomfortably warm (sometimes hot; occasionally sorta/kinda cool; not desired in summer).  I realize the HEAT flow lever on OFF setting is not designed to completely stop outlide air from going through the HB radiator but; rather, the air mixes with cold air from the cowl.  (Additional info:  With the temp lever on HOT, I can cook a beef roast.)

 

1.  In the COLD setting, shouldn't cowl air eventually (rapidly?) cool the radiator if the heater valve is closed so pass-through air to the footwell is not heated?  Seems so. 

2.  Any explanations for the aforementioned uncomfortable (at least in the summer) warm air?  I got none.

 

Thanks to all of you who have contributed so much HB information to 2002FAQ.  Such info has been exceedingly helpful during my Adventures into HB Refurbishments.

 

Larry

[732002Malaga]

I used this when I did mine.  Its possible that the control valve is not closed all the way, letting some hot water enter the HB Core.  IIRC, The bowden cable operated the flap and the valve at the same time. 

 

I also added a one way valve to the return side, to ensure that no hot water was working its way back from the motor side.

 

Hope this helps.

 

 

[jim57759]

I will be watching this topic with interest.  I too, have a new heater valve and recently serviced heater box.  Even though the heat/cold lever is all the way over to cold, and the heat and defrost levers are all the way "off", there is still residual heat coming out on floor and in defrost slots.  Mine is a '75 and the '72 I had before was the same way.  Since I live in the mountains I am reluctant to completely bypass the heater, but I would love to know if there is something else that can be done.

[frank]

Your heater valve may be defective. I experienced similar symptoms and a new valve made it all good.

[732002Malaga]

Also, how is your foam inside of your HB?  Is it positioned properly and sufficient to keep the air inside the box, and not escaping past the bottom flaps?

[2002#3]

Good suggestions.  Thank you.  Will re-check at least the valve closure.  

-- The heater valve is new and I can see it close completely if I remove the inlet heater hose and look into the engine side inlet of the valve.  

-- Foam on all flaps is new and appeared to seal rather nicely before re-assemblies and re-installations.  Cannot check foam without the usual contortions and wrestling match.

 

[Mike Self]

Later cars--and by this I believe all squarelights--have a water control valve with a small hole in the valve body.  That allows a limited flow of (hot) coolant into the heater core even with the temp control lever all the way to cold.  This was designed to keep coolant from stagnating in the heater radiator, leading to gelling, etc. as could happen on earlier cars (never had a problem with either of my roundies).  You can plug that little hole with a suitably sized plug or replace the valve with one from an earlier car.

 

Second possibility--are you sure you replaced the arm on the heater valve in its correct position.  It's VERY easy to reverse the arm so that with the temp lever set to cold, the valve is open, and vice versa.  

 

cheers

mike

 

 

[jgerock]

21 hours ago, mike said:

Later cars--and by this I believe all squarelights--have a water control valve with a small hole in the valve body.  That allows a limited flow of (hot) coolant into the heater core even with the temp control lever all the way to cold.  This was designed to keep coolant from stagnating in the heater radiator, leading to gelling, etc. as could happen on earlier cars (never had a problem with either of my roundies).  You can plug that little hole with a suitably sized plug or replace the valve with one from an earlier car.

 

Second possibility--are you sure you replaced the arm on the heater valve in its correct position.  It's VERY easy to reverse the arm so that with the temp lever set to cold, the valve is open, and vice versa.  

 

cheers

mike

 

 

See the little channel cut into the valve body on my 73. That is I believe the water path used to keep the flow of coolant from stagnating in the heater core.

[2002#3]

Well, there it is!  I was told today at a garage that sucker was there and you proved it.  

 

Thank you.

 

Larry

[Healey3000]

Hi,

 

I can see how the bypass flow can generate marginal heat in the cabin but if the air is uncomfortably hot, something else must be contributing.  In addition, you mention that the air ranges from hot to cool so again, there's seemingly another variable at play.

 

On my '74 I have noticed that the air is a touch warm but I have not inspected the valve and have been assuming it is defective.  I will be watching this topic with interest.